What this tells me is that DT has two more years - if not, it's probably going to be a wait until a particularly slow year.

http://www.profootballhof.com/history/Eligibility.jsp

Election by year of eligibilty & year as finalist

Since 1970 * Senior Candidate

– In those cases when a player’s career ended prior to 1963, the year of eligibility is based on the amount of years since the Hall opened in 1963 rather than the years from when the player last played.
– Prior to 1970, the procedure of naming 15 finalists was not defined. In 2007 Hall of Fame bylaws increased the number of finalists to 17.